Some aspects of reproductive biology of Capoeta razii, an endemic cyprinid species from the Sefid River in the southern Caspian Sea basin, were studied by monthly sampling throughout a year. Age, growth, sex ratio, spawning season, fecundity, gonadosomatic, modified gonado-somatic and Dobriyal indices were estimated. The sex ratio (F: M) was obtained as 1. 00: 2. 63, and the percentage of males was greater than females. The mature males and females were longer than 88 and 148 mm in total length, and 1+ and 2+ in age, respectively. The spawning of C. razii took place from late May to late August when the water temperature was between 19. 7 and 22. 8◦ C. At the beginning of the reproduction period, the average gonado-somatic index values were 10. 0% ranging from 4. 03% to 15. 90% in ripe females. The estimated gonadal indices showed that the ripe males were ready to spawn earlier than females. The average egg diameter was 0. 99± 0. 65, ranging from 0. 2 to 2. 3 mm. The averages absolute and relative fecundity were 4386± 2174 and 66. 3± 37. 8, respectively. The absolute fecundity was significantly related to body weight and gonad weight.